Our standard wheat flour contains only the endosperm and represents practically a 75 per cent. extraction. The remaining 25 per cent. is known in the trade as grain offal or mill-feed, and is used largely as a concentrated food for live stock, being prized in the feeding of dairy cattle.

[…] the fragments are broken down and the finer particles are collected by sieving; finally, there is the bolting of the assembled fine fractions, with exclusion of the wheat offal which includes bran and a number of other commercial fractions like red dog and shorts.